Translating device



Jan. 11, 1927. ,6 3,927

- O.E.BUCKLEY TRANSLATING DEVICE Filed Nov. 20, 1922 Patented Jan. 11, 1927.

UNITED STATES 1,613,927 PATENT OFFICE.

OLIVER E. BUCKLEY, OF MAPLEWOOD, NEW JERSEY, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TRANSLATING DEVICE.

Application filed November 20,1922. Serial No. 602,029.

This invention relates to translating de vices, particularly repeaters or amplifiers of the electron discharge type and its object is to repeat or amplify or otherwise translate signals without distortion.

As is well known in the art the input voltage output current characteristic of a vacuum tube of the three electrode type is approximately straight over only a narrow by providing, for example,

range of input voltage and for values outside of said range there is an appreciable curvature of the characteristic. This curvature, of course, is objectionable for the faithful repetition of alternating current if the tube is worked with input voltages of sufficient magnitude.

In accordance with this invention the curved characteristic of an electric discharge device such as a vacuum tube repeater of the three electrode type is made approximately straight over a wide range of input voltage two tubes or devices so connected that distortion in one tube is substantially reduced by the distortion in another. One way in which this may be accomplished is to connect two devices 1n parallel relation,-each normally having different s ace current values for the same input v0 tage. Signals to be transmitted either in modified or unmodified form through the'device are impressed upon the two tubes in such a manner that voltages of like sign are simultaneously impressed upon the two control electrodes, while the outgo-' in line is solconnected to the output circuits of the tubes that the space currents subtract and only the difference in the two space currents is impressed upon the outgoing line. Referring in detail to the drawings, Fig. 1 represents the invention embodied in a repeater circuit in which the incoming line is .directly connected in the input circuit of the amplifiers.

Fig. 2 illustrates the input voltage output current characteristic curves for the amplifying tubes of Fig. 1.

Fig. 3 is a modification of Fig. 1 1n which both theincoming line and the outgoing line are inductively coupled tothe amplifier.

Fig. 4 is a modification of Fig. 1 in which the output of the repeater is impressed directly upon .a galvanometer suspension such as that employed in an oscillograph.

Referring more particularly to Fig. 1 a

repeater is disclosed therein comprising two vacuum tubes. 7 and 8 connected in parallel relation which comprise cathodes 10 and 11, control electrodes 12 and 13 and anodes 14 and 15. The input circuit for tube 7 comprises cathode 10, the incoming signaling line 16, a source of voltage 17 and control electrode 12, while the input circuit for tube 8 comprises cathode 11. incoming line 16 and control electrode 13. The output circuit of tube 7 comprisesanode 14, a resistance 18 and the source of space current 19, while the output circuit for tube 8 comprises anode 15, a resistance 20 similar to resistance 18 and the source of voltage 19. Connected across the outside terminals of resistances 18 and 20 is the primary winding of the output transformer 21 which serves to couple the two output circuits to the outgoing line 22. Suitable heating current for the filaments 10 and 11 may be supplied by a source of voltage '23 connected in the usual manner.

With the connections above noted and assumingthe tubes 7 and 8 are of similar structure, tube 8 will operate with a greater space current than tube 7 for a given condition in line 16 for the reason that control electrode 12 is maintained at a negative potential with respect to its cathode 10 by the potential of source of voltage 17, while the only source of voltage included between the input electrodes of tube 8 is due to potentials present in line 16. The relation between the input voltage from line 16 and the output current of each tube is illustrated in Fig. 2 wherein the curve 23 represents the line input voltage vs. output current for the tube 8, while curve 24 illustrates the corresponding relation for tube 7, the difference between curves 23 and 24 being due to the presence of source of voltage 17 in the input circuit of tube 7, so that tube 7 requires a different input voltage from line 16 than. is required by tube 8 in order to reduce the space current to zero. I

Due to the fact that a given input voltage from line 16 produces voltage of like sign upon the two control electrodes 12 and 13, the space current in tube 7 will increase simultaneously with an increase in tube 8 and a decrease in the space current of the two tubes will take place simultaneously. This results in that the A. C. voltage developed across the outside terminals 25 and 26 characteristic of the repeaters as shown by the curve 27 of Fig. 2 which is obtained by subtracting ordinates of curve 24.from the corresponding ordinates of curve 23. This is an accurate representation of what takes place in the operation of tubes 7 and 8, since 'the outgoing line 22 receives current proportional to the difference between the space current in the two tubes. Due to the particular arrangement described above it follows that the amplifying tubes will be able to impress upon line 22 a more faithful amplified copy of the currents present in line 16 for the reason that the particular arrangement described provides a linear relation between input voltage and output current over a wide range of impressed voltage. This invention, however, is not limited to the particular arrangement above described for obtaining difl'erent space current values in two tubes for a given condition of line voltage since such may be obtained by other suitable arrangements known in the art. For example, the tubes 7 and 8 may not be similar, but one may have an appreciably difi'erent vacuum or different electrode relationship resultin in unequal space current for similar circuit conditions. a

Fig. 3 is similar to Fig. 1 in that a sourc of-voltage 28 is inserted in the input circuit of one of the tubes 29 while there is no corresponding source of voltage in the input circuit of the other tube 30. The incomlng line 31 is-coupled to the common branch of the two input circuits by a transformer 32, while the resistances '18 and 20 of Fig. 1 are eliminated andthc output'current passes directly through the two halves of the primary winding ofthe output transformer 33, which couples the tubes to the outgoing line. The operation of the arrangement of Fig. 3 is identical with that of Fig. 1 since tube 30 will operate with a greater space current than tube 29 and the outgoing line will receive current proportional to the difference in the space current of the two tubes.

- Fig. 4 is similar to Fig. 3 in that the incoming line is coupled to the common branch of the input circuit of the two amplifiers 34 and 35 by an input transformed 36, a source of voltage 37 being included in the in'dividu al portion of the input circuit for tube 34, but the output currents from the two tubes 34 and 35 are made to pass differentially through the two halves 38 and 39 of a galvanometer suspension, for example, such as that employed in oscillographs. The deflection of this galvanometer suspension will, therefore, be proportional to the difference in the space current ofthe two tubes 34 and 35 and this deflection will, therefore, represent more accurately an amplified copy of the alternating current present in the input line connected to transformer 36 than would be possible by the use of only one of the tubes alone,'for example, as explained above in connection with the curves illustrated in Fig. 2.

This invention has been described above as applied to vacuum tube amplifier circuits, but it is obvious that the invention is also applicable to circuits in which the vacuum tubes are not necessarily employed solely in the amplification and repeating of signals. It is also to be. understood that various other modifications may be made in the form of this invention above described without departing in any wise from. the spirit of the invention as defined inthe appended claims.

The inventionclaimed is: A

1. In combination, two space discharge devices, an input circuit for each device comprising a control electrode, said input circuits having a portion in common to each controlv electrode and another portion individual to each control electrode, means for supplying signaling current to the said common portion, means for biasing at least one of the control electrodes so that for different valuesof applied electromotive force a constant difference of potential 'is maintained between said control electrodes, means for establishing a space current tlow in each of said devices, the space current in one device being of a dilferent magnitude than the space current in the other device in the absence of signaling currents impressed on said control electrodes, an out oing line, and means for impressing on said line voltages proportional to the difference between the space currents in said devices.

2. In combination, two space discharge devices, each having an input circuit comprising a control electrode and an output circuit, each of said circuits having a portion in common .and a portion individual to said devices, means for biasing one of said control electrodes so that for varying values of applied electromotive force, a constant potential difference is maintained between said control electrodes, means for impress-' mg signaling currents upon the common portion of said input circuits, means for establishing a normally greater space cur-' rent in one of said devices than in the other in the absence of said signaling currents, and means responsive to the difference between the space currents in said devices in the individual portions of said output cir cuits.

8. In an amplifier comprising a pair of space discharge devices, an input circuit comprising acontrol electrode, and an output circuit for each of said devices, means for impressing potentials of like sign simultaneously on both control electrodes of said devices, and means for subtracting the outputs of said devices. I

4. In an amplifier comprising a pair of space discharge devices each having an anode, means for biasing at least one of the control electrodes so that for the same im-.

pressed electromotive force on both control electrodes space currents of different magnitudes are produced in said devices, means for impressing a voltage on both electrodes alike, and means for subtracting'the outputs of said devices. i

5. In an amplifier, a pair of space discharge devices each comprisingcan anode,

a cathode and a control electrode,

cathode and control electrode, each of said devices having a non-linear grid Volta espace current characteristic, means or maintaining a constant diflerence of potential between said control electrodes to establish a normally greater space current in one of said devices than in the other of said devices, means for impressing signaling voltages of like sign simultaneously on both of said control electrodes, and an outgoing circuit differentially related to the cathode anode circuits of said devices, the input voltage-output current characteristic of said amplifier as a whole being substantially linear over a widerange of input voltage.

In witness whereof, I hereunto subscribe my name this 14th day of November A. D.,

OLIVER E. BUCKLEY. 

